Regulation of host gene expression by HIV-1 TAR microRNAs

Background: The transactivating response (TAR) element of human immunodeficiency virus type 1 (HIV-1) is the source of two functional microRNAs (miRNAs), miR-TAR-5p and miR-TAR-3p. The objective of this study was to characterize the post-transcriptional regulation of host messenger RNAs (mRNAs) relevant to HIV-1 pathogenesis by HIV-1 TAR miRNAs. Results: We demonstrated that TAR miRNAs derived from HIV-1 can incorporate into host effector Argonaute protein complexes, which is required if these miRNAs are to regulate host mRNA expression. Bioinformatic predictions and reporter gene activity assays identified regulatory elements complementary and responsive to miR-TAR-5p and miR-TAR-3p in the 3’ untranslated region (UTR) of several candidate genes involved in apoptosis and cell survival. These include Caspase 8, Aiolos, Ikaros and Nucleophosmin (NPM)/B23. Analyses of Jurkat cells that stably expressed HIV-1 TAR or contained a full-length latent HIV provirus suggested that HIV-1 TAR miRNAs could regulate the expression of genes in T cells that affect the balance between apoptosis and cell survival. Conclusions: HIV-1 TAR miRNAs may contribute to the replication cycle and pathogenesis of HIV-1, by regulating host genes involved in the intricate balance between apoptosis and infected cell, to induce conditions that promote HIV-1 propagation and survival

RAN Nucleo-Cytoplasmic Transport and Mitotic Spindle Assembly Partners XPO7 and TPX2 Are New Prognostic Biomarkers in Serous Epithelial Ovarian Cancer

<div><p>Purpose</p><p>Epithelial ovarian cancer has the highest mortality rate of all gynecological malignancies. We have shown that high RAN expression strongly correlates with high-grade and poor patient survival in epithelial ovarian cancer. However, as RAN is a small GTPase involved in two main biological functions, nucleo-cytoplasmic transport and mitosis, it is still unknown which of these functions associate with poor prognosis.</p><p>Methods</p><p>To examine the biomarker value of RAN network components in serous epithelial ovarian cancer, protein expression of six specific RAN partners was analyzed by immunohistochemistry using a tissue microarray representing 143 patients associated with clinical parameters. The RAN GDP/GTP cycle was evaluated by the expression of RANBP1 and RCC1, the mitotic function by TPX2 and IMPβ, and the nucleo-cytoplasmic trafficking function by XPO7, XPOT and IMPβ.</p><p>Results</p><p>Based on Kaplan-Meier analyses, RAN, cytoplasmic XPO7 and TPX2 were significantly associated with poor overall patient survival, and RAN and TPX2 were associated with lower disease free survival in patients with high-grade serous carcinoma. Cox regression analysis revealed that RAN and TPX2 expression were independent prognostic factors for both overall and disease free survival, and that cytoplasmic XPO7 expression was a prognostic factor for overall patient survival.</p><p>Conclusions</p><p>In this systematic study, we show that RAN and two protein partners involved in its nucleo-cytoplasmic and mitotic functions (XPO7 and TPX2, respectively) can be used as biomarkers to stratify patients based on prognosis. In particular, we reported for the first time the clinical relevance of the exportin XPO7 and showed that TPX2 expression had the strongest prognostic value. These findings suggest that protein partners in each of RAN’s functions can discriminate between different outcomes in high-grade serous epithelial ovarian cancer patients. Furthermore, these proteins point to cellular processes that may ultimately be targeted to improve the survival in serous epithelial ovarian cancer.</p></div

RAN, XPO7 and TPX2 expressions are associated with poor survival in high-grade serous epithelial ovarian cancer.

<p>Expression of RAN network proteins was evaluated as prognostic indicators in only the high-grade serous carcinomas by Kaplan–Meier analysis. Survival was defined as the time from surgery to death from ovarian cancer or last follow-up. The log-rank test was used to define statistical difference between groups. For panels A–H, low staining (blue line) defined by values <1, medium staining (green line) defined by = 1<2 and high staining (pink line) defined as ≥2. For panel I, samples are scored as negative (black line) or positive (grey line) for TPX2 staining. In A–I, p denotes significance among all groups. For panels J–K, negative TPX2 staining with low staining intensity of RAN (J –black line) or XPO7 (K – black line); negative TPX2 staining with medium+high staining of RAN (J – cyan line) or XPO7 (K – violet line); positive TPX2 staining with medium+high staining of RAN (J – grey line) or XPO7 (K – grey line). In J–K, p (top right hand corner) is calculated for black versus cyan (RAN, panel J) or violet (XPO7, panel K). In J–K, p (bottom left hand corner) is calculated for grey versus cyan (RAN, panel J) or violet (XPO7, panel K). A–K, p<0.05 are indicated in bold letters.</p

Intensity of RAN network proteins in low-grade and high-grade serous epithelial ovarian cancer.

<p>For each protein, the staining intensity was defined as 0 (no staining), 1 (weak staining), 2 (moderate staining) or 3 (dark staining) within the epithelial compartment by two independent observers. The mean of the staining intensity for each protein was compared between low grade (white bars) and high grade tumors (grey bars) using a Student test. *p<0.05 **p≤0.005.</p

Univariate and multivariate Cox regression analyses. Statistical association between the expression of RAN or its partners and HG serous patient outcomes.

<p>*Overall survival is the time from the date of primary resection until either death due to ovarian cancer or last follow-up.</p><p>**Disease free survival is the time from the first resection of the primary tumor until the first event of recurrence.</p><p>Residual disease = amount of residual disease at time of primary resection of the ovarian tumor.</p><p>p = p-value. HR = hazard ratio. Bold fonts denote significant values.</p